This invention generally relates to proximity sensors. More particularly, this invention relates to a proximity sensor device that is also capable of determining at least one physical characteristic of the item of interest.
Proximity sensors are used in manufacturing and material handling applications for detecting the presence or placement of metal work pieces. Generally, proximity sensors generate a magnetic field from an inductor coil. When a metal work piece is brought into the magnetic field emitted from the sensor, eddy current losses in the metal work piece cause the impedance of the inductor coil to decrease. The decrease in impedance of the inductor coil is detected in appropriate circuitry that indicates the presence of the metal work piece in the magnetic field.
Common sensor arrangements typically include separate sensors for detecting the presence of a part and separate sensors for determining physical characteristics of the part, such as material thickness. Other sensor arrangements include proximity sensors that have switch actuated components that require physical contact with the part to determine one or more features of the part.
A disadvantage associated with current systems is that a plurality of individual sensors are required. Those skilled in the art are always striving to make improvements and to enhance the available technology.
This invention addresses the need for simplifying the overall sensor arrangement by integrating multiple functions into a single sensor device.